Gerry Adams accused the US government of “bizarre” behaviour on Monday after a meeting with a senior official in Washington DC was postponed.

At the weekend, Stormont First Minister Peter Robinson and Deputy First Minister Martin McGuinness cancelled plans to go to America to meet President Barack Obama on St Patrick’s Day to concentrate on finding a deal on welfare reform.

A meeting of Northern Ireland’s main party leaders is expected later this week.

US State Department envoy to Northern Ireland Gary Hart urged all parties last week to reach an understanding on the issue so that a successful series of meetings planned for Tuesday could go ahead.

Mr Adams has travelled to the US. He said: “The State Department’s handling of the issue of a meeting with me is bizarre.

“It serves no purpose other than to distract attention from the main issue. That is the full implementation of the Stormont House Agreement. That is Sinn Fein’s main focus. And Martin McGuinness and Peter Robinson are working on this as we speak.

“It is no skin off my nose not to meet the State Department. I am more concerned with protecting the rights and entitlements of citizens back home. That will remain Sinn Fein’s firm objective.”

Last week republicans withdrew support for welfare legislation as part of the Stormont House Agreement.

Finance Minister Simon Hamilton has said no additional money can be allocated to resolve the impasse. Talks are continuing and the five Executive party leaders and Northern Ireland Secretary Theresa Villiers are expected to meet later this week.

Finance Minister Simon Hamilton

Welfare changes were a crucial part of the agreement which prevented the collapse of the devolved institutions.

Sinn Fein has accused the DUP of bad faith and not doing what it said it would do. The DUP said the money had never been available for everything Sinn Fein wanted.

A Sinn Fein spokesman said: “Gerry Adams has a very busy schedule in the US. Sinn Fein had not confirmed a meeting with the State Department. Sinn Fein believes this story is someone setting out to cause mischief.

“This is a question for the State Department, not Sinn Fein.

“Gerry Adams will be in the White House tomorrow for the St Patrick’s Day celebrations.”